summaryrefslogtreecommitdiff
path: root/source3/nmbd/nmbd_elections.c
blob: db32461f060f91a19bb0041ef0f97b6056ca33d3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
/* 
   Unix SMB/CIFS implementation.
   NBT netbios routines and daemon - version 2
   Copyright (C) Andrew Tridgell 1994-1998
   Copyright (C) Luke Kenneth Casson Leighton 1994-1998
   Copyright (C) Jeremy Allison 1994-2003
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
   
*/

#include "includes.h"

/* Election parameters. */
extern time_t StartupTime;

/****************************************************************************
  Send an election datagram packet.
**************************************************************************/

static void send_election_dgram(struct subnet_record *subrec, const char *workgroup_name,
                                uint32 criterion, int timeup,const char *server_name)
{
	pstring outbuf;
	unstring srv_name;
	char *p;

	DEBUG(2,("send_election_dgram: Sending election packet for workgroup %s on subnet %s\n",
		workgroup_name, subrec->subnet_name ));

	memset(outbuf,'\0',sizeof(outbuf));
	p = outbuf;
	SCVAL(p,0,ANN_Election); /* Election opcode. */
	p++;

	SCVAL(p,0,((criterion == 0 && timeup == 0) ? 0 : ELECTION_VERSION));
	SIVAL(p,1,criterion);
	SIVAL(p,5,timeup*1000); /* ms - Despite what the spec says. */
	p += 13;
	unstrcpy(srv_name, server_name);
	strupper_m(srv_name);
	/* The following call does UNIX -> DOS charset conversion. */
	pstrcpy_base(p, srv_name, outbuf);
	p = skip_string(outbuf,sizeof(outbuf),p);
  
	send_mailslot(False, BROWSE_MAILSLOT, outbuf, PTR_DIFF(p,outbuf),
		global_myname(), 0,
		workgroup_name, 0x1e,
		subrec->bcast_ip, subrec->myip, DGRAM_PORT);
}

/*******************************************************************
 We found a current master browser on one of our broadcast interfaces.
******************************************************************/

static void check_for_master_browser_success(struct subnet_record *subrec,
                                 struct userdata_struct *userdata,
                                 struct nmb_name *answer_name,
                                 struct in_addr answer_ip, struct res_rec *rrec)
{
	unstring aname;
	pull_ascii_nstring(aname, sizeof(aname), answer_name->name);
	DEBUG(3,("check_for_master_browser_success: Local master browser for workgroup %s exists at \
IP %s (just checking).\n", aname, inet_ntoa(answer_ip) ));
}

/*******************************************************************
 We failed to find a current master browser on one of our broadcast interfaces.
******************************************************************/

static void check_for_master_browser_fail( struct subnet_record *subrec,
                                           struct response_record *rrec,
                                           struct nmb_name *question_name,
                                           int fail_code)
{
	unstring workgroup_name;
	struct work_record *work;

	pull_ascii_nstring(workgroup_name,sizeof(workgroup_name),question_name->name);

	work = find_workgroup_on_subnet(subrec, workgroup_name);
	if(work == NULL) {
		DEBUG(0,("check_for_master_browser_fail: Unable to find workgroup %s on subnet %s.=\n",
			workgroup_name, subrec->subnet_name ));
		return;
	}

	if (strequal(work->work_group, lp_workgroup())) {

		if (lp_local_master()) {
			/* We have discovered that there is no local master
				browser, and we are configured to initiate
				an election that we will participate in.
			*/
			DEBUG(2,("check_for_master_browser_fail: Forcing election on workgroup %s subnet %s\n",
				work->work_group, subrec->subnet_name ));

			/* Setting this means we will participate when the
				election is run in run_elections(). */
			work->needelection = True;
		} else {
			/* We need to force an election, because we are configured
				not to become the local master, but we still need one,
				having detected that one doesn't exist.
			*/
			send_election_dgram(subrec, work->work_group, 0, 0, "");
		}
	}
}

/*******************************************************************
  Ensure there is a local master browser for a workgroup on our
  broadcast interfaces.
******************************************************************/

void check_master_browser_exists(time_t t)
{
	static time_t lastrun=0;
	struct subnet_record *subrec;
	const char *workgroup_name = lp_workgroup();

	if (!lastrun)
		lastrun = t;

	if (t < (lastrun + (CHECK_TIME_MST_BROWSE * 60)))
		return;

	lastrun = t;

	dump_workgroups(False);

	for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec)) {
		struct work_record *work;

		for (work = subrec->workgrouplist; work; work = work->next) {
			if (strequal(work->work_group, workgroup_name) && !AM_LOCAL_MASTER_BROWSER(work)) {
				/* Do a name query for the local master browser on this net. */
				query_name( subrec, work->work_group, 0x1d,
					check_for_master_browser_success,
					check_for_master_browser_fail,
					NULL);
			}
		}
	}
}

/*******************************************************************
  Run an election.
******************************************************************/

void run_elections(time_t t)
{
	static time_t lastime = 0;
  
	struct subnet_record *subrec;
  
	START_PROFILE(run_elections);

	/* Send election packets once every 2 seconds - note */
	if (lastime && (t - lastime < 2)) {
		END_PROFILE(run_elections);
		return;
	}
  
	lastime = t;
  
	for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec)) {
		struct work_record *work;

		for (work = subrec->workgrouplist; work; work = work->next) {
			if (work->RunningElection) {
				/*
				 * We can only run an election for a workgroup if we have
				 * registered the WORKGROUP<1e> name, as that's the name
				 * we must listen to.
				 */
				struct nmb_name nmbname;

				make_nmb_name(&nmbname, work->work_group, 0x1e);
				if(find_name_on_subnet( subrec, &nmbname, FIND_SELF_NAME)==NULL) {
					DEBUG(8,("run_elections: Cannot send election packet yet as name %s not \
yet registered on subnet %s\n", nmb_namestr(&nmbname), subrec->subnet_name ));
					continue;
				}

				send_election_dgram(subrec, work->work_group, work->ElectionCriterion,
						t - StartupTime, global_myname());
	      
				if (work->ElectionCount++ >= 4) {
					/* Won election (4 packets were sent out uncontested. */
					DEBUG(2,("run_elections: >>> Won election for workgroup %s on subnet %s <<<\n",
						work->work_group, subrec->subnet_name ));

					work->RunningElection = False;

					become_local_master_browser(subrec, work);
				}
			}
		}
	}
	END_PROFILE(run_elections);
}

/*******************************************************************
  Determine if I win an election.
******************************************************************/

static bool win_election(struct work_record *work, int version,
                         uint32 criterion, int timeup, const char *server_name)
{  
	int mytimeup = time(NULL) - StartupTime;
	uint32 mycriterion = work->ElectionCriterion;

	/* If local master is false then never win in election broadcasts. */
	if(!lp_local_master()) {
		DEBUG(3,("win_election: Losing election as local master == False\n"));
		return False;
	}
 
	DEBUG(4,("win_election: election comparison: %x:%x %x:%x %d:%d %s:%s\n",
			version, ELECTION_VERSION,
			criterion, mycriterion,
			timeup, mytimeup,
			server_name, global_myname()));

	if (version > ELECTION_VERSION)
		return(False);
	if (version < ELECTION_VERSION)
		return(True);
  
	if (criterion > mycriterion)
		return(False);
	if (criterion < mycriterion)
		return(True);

	if (timeup > mytimeup)
		return(False);
	if (timeup < mytimeup)
		return(True);

	if (StrCaseCmp(global_myname(), server_name) > 0)
		return(False);
  
	return(True);
}

/*******************************************************************
  Process an incoming election datagram packet.
******************************************************************/

void process_election(struct subnet_record *subrec, struct packet_struct *p, char *buf)
{
	struct dgram_packet *dgram = &p->packet.dgram;
	int version = CVAL(buf,0);
	uint32 criterion = IVAL(buf,1);
	int timeup = IVAL(buf,5)/1000;
	unstring server_name;
	struct work_record *work;
	unstring workgroup_name;

	START_PROFILE(election);

	pull_ascii_nstring(server_name, sizeof(server_name), buf+13);
	pull_ascii_nstring(workgroup_name, sizeof(workgroup_name), dgram->dest_name.name);

	server_name[15] = 0;  

	DEBUG(3,("process_election: Election request from %s at IP %s on subnet %s for workgroup %s.\n",
		server_name,inet_ntoa(p->ip), subrec->subnet_name, workgroup_name ));

	DEBUG(5,("process_election: vers=%d criterion=%08x timeup=%d\n", version,criterion,timeup));

	if(( work = find_workgroup_on_subnet(subrec, workgroup_name)) == NULL) {
		DEBUG(0,("process_election: Cannot find workgroup %s on subnet %s.\n",
			workgroup_name, subrec->subnet_name ));
		goto done;
	}

	if (!strequal(work->work_group, lp_workgroup())) {
		DEBUG(3,("process_election: ignoring election request for workgroup %s on subnet %s as this \
is not my workgroup.\n", work->work_group, subrec->subnet_name ));
		goto done;
	}

	if (win_election(work, version,criterion,timeup,server_name)) {
		/* We take precedence over the requesting server. */
		if (!work->RunningElection) {
			/* We weren't running an election - start running one. */

			work->needelection = True;
			work->ElectionCount=0;
		}

		/* Note that if we were running an election for this workgroup on this
			subnet already, we just ignore the server we take precedence over. */
	} else {
		/* We lost. Stop participating. */
		work->needelection = False;

		if (work->RunningElection || AM_LOCAL_MASTER_BROWSER(work)) {
			work->RunningElection = False;
			DEBUG(3,("process_election: >>> Lost election for workgroup %s on subnet %s <<<\n",
				work->work_group, subrec->subnet_name ));
			if (AM_LOCAL_MASTER_BROWSER(work))
				unbecome_local_master_browser(subrec, work, False);
		}
	}
done:

	END_PROFILE(election);
}

/****************************************************************************
  This function looks over all the workgroups known on all the broadcast
  subnets and decides if a browser election is to be run on that workgroup.
  It returns True if any election packets need to be sent (this will then
  be done by run_elections().
***************************************************************************/

bool check_elections(void)
{
	struct subnet_record *subrec;
	bool run_any_election = False;

	for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec)) {
		struct work_record *work;
		for (work = subrec->workgrouplist; work; work = work->next) {
			run_any_election |= work->RunningElection;

			/* 
			 * Start an election if we have any chance of winning.
			 * Note this is a change to the previous code, that would
			 * only run an election if nmbd was in the potential browser
			 * state. We need to run elections in any state if we're told
			 * to. JRA.
			 */

			if (work->needelection && !work->RunningElection && lp_local_master()) {
				/*
				 * We can only run an election for a workgroup if we have
				 * registered the WORKGROUP<1e> name, as that's the name
				 * we must listen to.
				 */
				struct nmb_name nmbname;

				make_nmb_name(&nmbname, work->work_group, 0x1e);
				if(find_name_on_subnet( subrec, &nmbname, FIND_SELF_NAME)==NULL) {
					DEBUG(8,("check_elections: Cannot send election packet yet as name %s not \
yet registered on subnet %s\n", nmb_namestr(&nmbname), subrec->subnet_name ));
					continue;
				}

				DEBUG(3,("check_elections: >>> Starting election for workgroup %s on subnet %s <<<\n",
					work->work_group, subrec->subnet_name ));

				work->ElectionCount = 0;
				work->RunningElection = True;
				work->needelection = False;
			}
		}
	}
	return run_any_election;
}

/****************************************************************************
 Process a internal Samba message forcing an election.
***************************************************************************/

void nmbd_message_election(struct messaging_context *msg,
			   void *private_data,
			   uint32_t msg_type,
			   struct server_id server_id,
			   DATA_BLOB *data)
{
	struct subnet_record *subrec;

	for (subrec = FIRST_SUBNET; subrec; subrec = NEXT_SUBNET_EXCLUDING_UNICAST(subrec)) {
		struct work_record *work;
		for (work = subrec->workgrouplist; work; work = work->next) {
			if (strequal(work->work_group, lp_workgroup())) {
				work->needelection = True;
				work->ElectionCount=0;
				work->mst_state = lp_local_master() ? MST_POTENTIAL : MST_NONE;
			}
		}
	}
}